[PATCH] mmc: sdhci-cadence: fix logically and structurally dead code

[PATCH] mmc: sdhci-cadence: fix logically and structurally dead code

[Gustavo A. R. Silva]

Currently, the code block inside the for loop will never execute
more than once, because the function returns inmediately after
the first iteration, hence the execution of the code at the second
iteration is structurally dead and, code at line 281: return 0; is
never reached.

Based on the code comments, it seems that the actual intention is
to execute the code inside the for loop twice instead of once.

So, fix this issue by removing the return statement inside the for
loop and replace the "return 0" with "return ret".

Addresses-Coverity-ID: 1468009 ("Logically dead code")
Addresses-Coverity-ID: 1468002 ("Structurally dead code")
Fixes: 213fae74318b ("mmc: sdhci-cadence: send tune request twice to
work around errata")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/mmc/host/sdhci-cadence.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
index bc30d16..facbad8 100644
--- a/drivers/mmc/host/sdhci-cadence.c
+++ b/drivers/mmc/host/sdhci-cadence.c
@@ -275,10 +275,9 @@ static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
 					 !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
 					 0, 1);
 
-		return ret;
 	}
 
-	return 0;
+	return ret;
 }
 
 static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
-- 
2.7.4

Re: [PATCH] mmc: sdhci-cadence: fix logically and structurally dead code

[Masahiro Yamada]

Hi.


2018-04-19 22:53 GMT+09:00 Gustavo A. R. Silva <gustavo@embeddedor.com>:
> Currently, the code block inside the for loop will never execute
> more than once, because the function returns inmediately after
> the first iteration, hence the execution of the code at the second
> iteration is structurally dead and, code at line 281: return 0; is
> never reached.
>
> Based on the code comments, it seems that the actual intention is
> to execute the code inside the for loop twice instead of once.

Thanks for the report.

> So, fix this issue by removing the return statement inside the for
> loop and replace the "return 0" with "return ret".
>
> Addresses-Coverity-ID: 1468009 ("Logically dead code")
> Addresses-Coverity-ID: 1468002 ("Structurally dead code")
> Fixes: 213fae74318b ("mmc: sdhci-cadence: send tune request twice to
> work around errata")


Probably, this Fixes tag will dangle.

Ulf usually repeats git-rebase to build-up his pull-request.

The addressed commit was already rebased,
and its commit ID will change a few more times
since it is now -rc1.


A clean solution would be, to squash a fix-up into the original patch.
(This patch is not what I want, though.)

If you want to claim contribution in a separate patch,
please rewrite the code as I suggested,
and drop the Fixes tag.



> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/mmc/host/sdhci-cadence.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> index bc30d16..facbad8 100644
> --- a/drivers/mmc/host/sdhci-cadence.c
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -275,10 +275,9 @@ static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
>                                          !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
>                                          0, 1);
>
> -               return ret;
>         }
>
> -       return 0;
> +       return ret;
>  }
>
>  static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
> --

No.
I want to confirm that the operation succeeds twice.

Your code hides any error in the first loop.



My intention is like follows:



 --- a/drivers/mmc/host/sdhci-cadence.c
 +++ b/drivers/mmc/host/sdhci-cadence.c
 @@ -275,10 +275,9 @@ static int sdhci_cdns_set_tune_val(struct
sdhci_host *host, unsigned int val)
                                          !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
                                          0, 1);
 -
 -               return ret;
 +               if (ret)
 +                       return ret;
         }

         return 0;
  }

  static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)



-- 
Best Regards
Masahiro Yamada

Re: [PATCH] mmc: sdhci-cadence: fix logically and structurally dead code

[Gustavo A. R. Silva]

I got it.

I'll send v2 shortly.

Thanks for the feedback, Masahiro.

--
Gustavo

On 04/19/2018 10:42 AM, Masahiro Yamada wrote:
> Hi.
> 
> 
> 2018-04-19 22:53 GMT+09:00 Gustavo A. R. Silva <gustavo@embeddedor.com>:
>> Currently, the code block inside the for loop will never execute
>> more than once, because the function returns inmediately after
>> the first iteration, hence the execution of the code at the second
>> iteration is structurally dead and, code at line 281: return 0; is
>> never reached.
>>
>> Based on the code comments, it seems that the actual intention is
>> to execute the code inside the for loop twice instead of once.
> 
> Thanks for the report.
> 
>> So, fix this issue by removing the return statement inside the for
>> loop and replace the "return 0" with "return ret".
>>
>> Addresses-Coverity-ID: 1468009 ("Logically dead code")
>> Addresses-Coverity-ID: 1468002 ("Structurally dead code")
>> Fixes: 213fae74318b ("mmc: sdhci-cadence: send tune request twice to
>> work around errata")
> 
> 
> Probably, this Fixes tag will dangle.
> 
> Ulf usually repeats git-rebase to build-up his pull-request.
> 
> The addressed commit was already rebased,
> and its commit ID will change a few more times
> since it is now -rc1.
> 
> 
> A clean solution would be, to squash a fix-up into the original patch.
> (This patch is not what I want, though.)
> 
> If you want to claim contribution in a separate patch,
> please rewrite the code as I suggested,
> and drop the Fixes tag.
> 
> 
> 
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>> ---
>>   drivers/mmc/host/sdhci-cadence.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
>> index bc30d16..facbad8 100644
>> --- a/drivers/mmc/host/sdhci-cadence.c
>> +++ b/drivers/mmc/host/sdhci-cadence.c
>> @@ -275,10 +275,9 @@ static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
>>                                           !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
>>                                           0, 1);
>>
>> -               return ret;
>>          }
>>
>> -       return 0;
>> +       return ret;
>>   }
>>
>>   static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
>> --
> 
> No.
> I want to confirm that the operation succeeds twice.
> 
> Your code hides any error in the first loop.
> 
> 
> 
> My intention is like follows:
> 
> 
> 
>   --- a/drivers/mmc/host/sdhci-cadence.c
>   +++ b/drivers/mmc/host/sdhci-cadence.c
>   @@ -275,10 +275,9 @@ static int sdhci_cdns_set_tune_val(struct
> sdhci_host *host, unsigned int val)
>                                            !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
>                                            0, 1);
>   -
>   -               return ret;
>   +               if (ret)
>   +                       return ret;
>           }
> 
>           return 0;
>    }
> 
>    static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
> 
> 
>